Food products are commonly in some type of fluid form during and/or after processing. Extruders are often used to process various types of food products. Extruders are desirable because they can produce a large amount of a fluid food, which may be a food dough, for example, and more specifically a cooked food cereal dough in a short period of time. Moreover, it is advantageous to divide the fluid food extrudate or other mass food flow into a multiplicity of extrudate subflows by splitting the mass flow and directing these extrudate subflows into and through a plurality of corresponding separate passageways. This enables each extrudate substream to be further manipulated and processed. For example, an additive injection device can then be incorporated into each passageway thereby enabling a suitable type and quantity of fluid additive to be introduced into the extrudate subflow. Additives can be introduced to enhance the flavor, color or texture of the final food product. Thus, either a single food product with one or more desired characteristics (i.e., a ready-to-eat cereal of a desired color or with an assortment of differently flavored and/or colored pieces, for example) or a variety of distinct food products (i.e., an array of distinct snack foods derived from the common extrudate mass flow) can be produced by dividing the extrudate mass flow into subflows.
However, obtaining a desired degree of mixing or a homogenous mixture after introducing a fluid additive into a relatively viscous fluid food extrudate subflow or other fluid food product is troublesome. Typical food dough extrudates may have a viscosity in the range of from about 200,000 to 1,000,000 centipoise, for example. Upon introduction into a fluid food extrudate, a typically less viscous fluid additive (such as a colorant or flavorant) has a tendency to migrate to the exterior periphery of the extrudate where the additive tends to pool without blending with the food extrudate. This pooling at the extrudate's periphery prevents adequate blending of the additive throughout the extrudate mass by static mixers or other mixers located downstream from the additive injection point leaving undesirable pockets or areas of relatively high additive concentration in the extrudate mass.
Dividing a fluid food extrudate mass flow into subflows and subsequently introducing a fluid food additive has inherent shortcomings in addition to pooling or insufficient mixing. Introducing an additive injection device into the cross-sectional flow of the extrudate substream can substantially increase the pressure drop along the length of the passageway where the injection device is present. This increases the overall resistance in the system. When the original extrudate mass flow is divided into a plurality or many subflows, each travelling through a corresponding separate passageway, the additional energy required to drive the highly viscous fluid food extrudate to system's end can be substantial. Moreover, providing an independent additive supply for each additive injection device incorporated within each passageway makes it difficult to obtain a uniform introduction of additive in each of a plurality of extrudate sub flow passageways.
A need exists to more uniformly introduce the same amount of additive across a plurality of food extrudate subflows travelling through separate passageways. A need also exists to more effectively reduce pooling when additive is introduced. Finally, a need exists for an additive injector device that can be easily and readily cleaned and/or sanitized.